scholarly journals Concurrent polarization IR analysis to determine the 3D angles and the order parameter for molecular orientation imaging

2018 ◽  
Vol 26 (19) ◽  
pp. 24577
Author(s):  
Young Jong Lee
Keyword(s):  
Molecular Orientation ◽  
Order Parameter ◽  
Orientation Imaging ◽  
Ir Analysis

Polarized microbeam FT-IR analysis of single fibers

1996 ◽  
Vol 54 ◽  
pp. 206-207
Author(s):  
Liling Cho ◽  
David L. Wetzel
Keyword(s):  
Molecular Orientation ◽  
Transition Point ◽  
Polymer Fibers ◽  
Single Fiber ◽  
Wire Grid ◽  
Polyester Fibers ◽  
Ft Ir ◽  
Ir Analysis ◽  
The Relationship ◽  
Wire Grid Polarizer

Polarized infrared microscopy has been used for forensic purposes to differentiate among polymer fibers. Dichroism can be used to compare and discriminate between different polyester fibers, including those composed of polyethylene terephthalate that are frequently encountered during criminal casework. In the fiber manufacturering process, fibers are drawn to develop molecular orientation and crystallinity. Macromolecular chains are oriented with respect to the long axis of the fiber. It is desirable to determine the relationship between the molecular orientation and stretching properties. This is particularly useful on a single fiber basis. Polarized spectroscopic differences observed from a single fiber are proposed to reveal the extent of molecular orientation within that single fiber. In the work presented, we compared the dichroic ratio between unstretched and stretched polyester fibers, and the transition point between the two forms of the same fiber. These techniques were applied to different polyester fibers. A fiber stretching device was fabricated for use on the instrument (IRμs, Spectra-Tech) stage. Tension was applied with a micrometer screw until a “neck” was produced in the stretched fiber. Spectra were obtained from an area of 24×48 μm. A wire-grid polarizer was used between the source and the sample.

Molecular Orientation Imaging of Liquid Crystals by Tunable-Polarization-Mode Coherent Anti-Stokes Raman Scattering Microscopy

2013 ◽  
Vol 6 (7) ◽  
pp. 072401 ◽  
Author(s):  
Takeo Minamikawa ◽  
Tatsuro Takagi ◽  
Hirohiko Niioka ◽  
Makoto Kurihara ◽  
Nobuyuki Hashimoto ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Raman Scattering ◽  
Molecular Orientation ◽  
Polarization Mode ◽  
Orientation Imaging ◽  
Anti Stokes

Molecular Orientation in Uniaxial Liquid Crystal Phases as Studied by Electron Paramagnetic Resonance

1999 ◽  
Vol 54 (5) ◽  
pp. 299-304 ◽  
Author(s):  
Hanka Moryson ◽  
Danuta Bauman ◽  
Wojciech Hilczer ◽  
Stanislaw Hoffmann
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Liquid Crystal ◽  
Molecular Orientation ◽  
Order Parameter ◽  
Paramagnetic Resonance ◽  
Optical Birefringence ◽  
Dichroic Dye ◽  
Crystal Phases ◽  
Electron Paramagnetic ◽  
Uniaxial Liquid Crystal

Abstract The electron paramagnetic resonance spectra of 3/ß-doxyl-5α-cholestane dissolved in five liquid crystals have been recorded as a function of temperature in the isotropic and mesogenic phases. From these spectra the order parameter (P2) has been determined. The results have been com-pared with the data obtained from the optical birefringence measurements and from the polarized absorption spectra of the dichroic dye dissolved in liquid crystal host.

Photoresponsive Liquid Crystalline Polymeric Materials

2012 ◽  
Vol 77 ◽  
pp. 325-332 ◽  
Author(s):  
Dan Qing Liu ◽  
Casper Van Oosten ◽  
Cees W.M. Bastiaansen ◽  
Dirk J. Broer
Keyword(s):  
Molecular Orientation ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Polymer Networks ◽  
Polymeric Materials ◽  
Molecular Organization ◽  
Surface Topology ◽  
Network Configuration ◽  
Lithographic Patterning

In-situ photopolymerization of liquid crystalline (LC) monomers has proven to be a valuable technique for the formation of well-ordered polymer networks. Their anisotropic properties led to a variety of applications in optics, electronics and mechanics. The use of light to initiate polymerization enables lithographic patterning. In addition the LC behavior enables formation of complex morphologies on molecular level. Controlling the director profile of an LC network film in transversal direction gives geometrical morphing upon minor changes in order parameter. Examples of suited profiles of molecular orientation are twisted or splayed director configurations tied up in the network configuration. Reversible order parameter changes can be induced by light using the photo-activated trans-cis isomerization of a copolymerized azobenzene monomer. This is demonstrated in photoresponsive cilia inkjet printed on a substrate. The cilia possess a splayed molecular organization and show well-controlled bending when addressed by light. We demonstrate a patterned film with alternating helicoidal and perpendicular-uniaxial molecular orientation. When applied as coating on glass, photo-activation in this case leads to a dynamically switching surface topology

Molecular topology of three ring nematogens from 13C–1H dipolar couplings

RSC Advances ◽  
2014 ◽  
Vol 4 (63) ◽  
pp. 33383-33390 ◽  
Author(s):  
Nitin P. Lobo ◽  
Bibhuti B. Das ◽  
T. Narasimhaswamy ◽  
K. V. Ramanathan
Keyword(s):  
Molecular Orientation ◽  
Order Parameter ◽  
Dipolar Couplings ◽  
Molecular Topology

A facile way of estimating the order parameter and the molecular orientation from 13C–1H dipolar couplings for three ring based nematogens with a terminal C–H vector.

Forensic applications of IR infrared microscopic internal reflection spectroscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1528-1529
Author(s):  
Edward G. Bartick ◽  
John A. Reffner
Keyword(s):  
Specular Reflection ◽  
Forensic Analysis ◽  
Attenuated Total Reflection ◽  
Internal Reflection ◽  
Standard Size ◽  
Ir Microscopy ◽  
Ir Analysis ◽  
Plastic Explosives ◽  
Internal Reflection Spectroscopy ◽  
Reflectance Measurements

Since the introduction of commercial Fourier transform infrared (FTIR) microscopic systems in 1983, IR microscopy has developed as an important analytical tool in research, industry and forensic analysis. Because of the frequent encounter of small quantities of physical evidence found at crime scenes, spectroscopic IR microscopes have proven particularly valuable for forensic applications. Transmittance and reflectance measurements have proven very useful. Reflection-absorption, specular reflection, and diffuse reflection have all been applied. However, it has been only very recently that an internal reflection (IRS) objective has been commercially introduced.The IRS method, also known as attenuated total reflection (ATR), has proven very useful for IR analysis of standard size samples. The method has been applied to adhesive tapes, plastic explosives, and general applications in the analysis of opaque materials found as evidence. The small quantities or uncontaminated areas of specimens frequently found requiring forensic analysis will often be directly applicable to microscopic IRS analysis.

Observing the relaxation of molecular orientation in sheared liquid crystalline polymer solutions

1990 ◽  
Vol 48 (4) ◽  
pp. 1092-1093
Author(s):  
Wendy Putnam ◽  
Christopher Viney
Keyword(s):  
Molecular Orientation ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Polymer Processing ◽  
Molecular Alignment ◽  
Global Alignment ◽  
Shear Direction ◽  
Axial Strength ◽  
Strength And Stiffness

Liquid crystalline polymers (solutions or melts) can be spun into fibers and films that have a higher axial strength and stiffness than conventionally processed polymers. These superior properties are due to the spontaneous molecular extension and alignment that is characteristic of liquid crystalline phases. Much of the effort in processing conventional polymers goes into extending and aligning the chains, while, in liquid crystalline polymer processing, the primary microstructural rearrangement involves converting local molecular alignment into global molecular alignment. Unfortunately, the global alignment introduced by processing relaxes quickly upon cessation of shear, and the molecular orientation develops a periodic misalignment relative to the shear direction. The axial strength and stiffness are reduced by this relaxation.Clearly there is a need to solidify the liquid crystalline state (i.e. remove heat or solvent) before significant relaxation occurs. Several researchers have observed this relaxation, mainly in solutions of hydroxypropyl cellulose (HPC) because they are lyotropic under ambient conditions.

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